using System;
using System.IO;
/*
 * $Id: BitFile.cs 177 2010-05-30 17:30:44Z psoares33 $
 * Copyright 2003-2008 by Paulo Soares.
 *
 * This code was originally released in 2001 by SUN (see class
 * com.sun.media.imageio.plugins.tiff.TIFFDirectory.java)
 * using the BSD license in a specific wording. In a mail dating from
 * January 23, 2008, Brian Burkhalter (@sun.com) gave us permission
 * to use the code under the following version of the BSD license:
 *
 * Copyright (c) 2005 Sun Microsystems, Inc. All  Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met: 
 * 
 * - Redistribution of source code must retain the above copyright 
 *   notice, this  list of conditions and the following disclaimer.
 * 
 * - Redistribution in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in 
 *   the documentation and/or other materials provided with the
 *   distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of 
 * contributors may be used to endorse or promote products derived 
 * from this software without specific prior written permission.
 * 
 * This software is provided "AS IS," without a warranty of any 
 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND 
 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
 * EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL 
 * NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF 
 * USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR 
 * ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
 * CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
 * REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
 * INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGES. 
 * 
 * You acknowledge that this software is not designed or intended for 
 * use in the design, construction, operation or maintenance of any 
 * nuclear facility. 
 */
namespace iTextSharp.text.pdf.codec {

    /**
     * Came from GIFEncoder initially.
     * Modified - to allow for output compressed data without the block counts
     * which breakup the compressed data stream for GIF.
     **/
    public class BitFile {
        Stream output_;
        byte[] buffer_;
        int index_;
        int bitsLeft_;	// bits left at current index that are avail.

        /** note this also indicates gif format BITFile. **/
        bool blocks_ = false;

        /**
         * @param output destination for output data
         * @param blocks GIF LZW requires block counts for output data
         **/
        public BitFile(Stream output, bool blocks) {
            output_ = output;
            blocks_ = blocks;
            buffer_ = new byte[256];
            index_ = 0;
            bitsLeft_ = 8;
        }

        public void Flush() {
            int numBytes = index_ + (bitsLeft_ == 8 ? 0 : 1);
            if (numBytes > 0) {
                if (blocks_)
                    output_.WriteByte((byte)numBytes);
                output_.Write(buffer_, 0, numBytes);
                buffer_[0] = 0;
                index_ = 0;
                bitsLeft_ = 8;
            }
        }

        public void WriteBits(int bits, int numbits) {
            int bitsWritten = 0;
            int numBytes = 255;		// gif block count
            do {
                // This handles the GIF block count stuff
                if ((index_ == 254 && bitsLeft_ == 0) || index_ > 254) {
                    if (blocks_)
                        output_.WriteByte((byte)numBytes);

                    output_.Write(buffer_, 0, numBytes);

                    buffer_[0] = 0;
                    index_ = 0;
                    bitsLeft_ = 8;
                }

                if (numbits <= bitsLeft_) { // bits contents fit in current index byte
                    if (blocks_) { // GIF
                        buffer_[index_] |= (byte)((bits & ((1 << numbits) - 1)) << (8 - bitsLeft_));
                        bitsWritten += numbits;
                        bitsLeft_ -= numbits;
                        numbits = 0;
                    }
                    else {
                        buffer_[index_] |= (byte)((bits & ((1 << numbits) - 1)) << (bitsLeft_ - numbits));
                        bitsWritten += numbits;
                        bitsLeft_ -= numbits;
                        numbits = 0;

                    }
                }
                else {	// bits overflow from current byte to next.
                    if (blocks_) { // GIF
                        // if bits  > space left in current byte then the lowest order bits
                        // of code are taken and put in current byte and rest put in next.
                        buffer_[index_] |= (byte)((bits & ((1 << bitsLeft_) - 1)) << (8 - bitsLeft_));
                        bitsWritten += bitsLeft_;
                        bits >>= bitsLeft_;
                        numbits -= bitsLeft_;
                        buffer_[++index_] = 0;
                        bitsLeft_ = 8;
                    }
                    else {
                        // if bits  > space left in current byte then the highest order bits
                        // of code are taken and put in current byte and rest put in next.
                        // at highest order bit location !! 
                        int topbits = (byte)(((uint)bits >> (numbits - bitsLeft_)) & ((1 << bitsLeft_) - 1));
                        buffer_[index_] |= (byte)topbits;
                        numbits -= bitsLeft_;	// ok this many bits gone off the top
                        bitsWritten += bitsLeft_;
                        buffer_[++index_] = 0;	// next index
                        bitsLeft_ = 8;
                    }
                }

            } while (numbits != 0);
        }
    }
}